Image-engraving plate



United States Patent Ollice 3,127,301 Patented Mar. 31, 1964 Delaware No Drawing. Filed Aug. 11, 1960, Ser. No. 48,825 9 Claims. (Cl. 161-6) This invention relates to image-engraving plates for reproducing images by either printing or photo-actinic processes and, while it is of general application, it is particularly suitable for use in the machine for producing screened relief pattern image plates of the type described in Patent Re. 23,914 of John A. Boyajean.

In aforesaid Patent Re. 23,914 there is described a machine designed and intended to be used in the place of well known photochemical processes for making plates from photographic prints, negatives, or other images for reproduction by printing or like processes. In general, that machine comprises a pair of synchronously rotatable cylinders for individually supporting a plate and an image sheet and a pair of reciprocable carriages individually including a photoelectric pick-up system and a platecleforming tool for respectively scanning the image sheet cylinder and the plate cylinder. The machine also includes means responsive to the output of the pick-up system for actuating the tool, means for reciprocating the carriages synchronously, and an electrical screen generator driven synchronously with the cylinders and connected to modulate the output of the pick-up system.

In Patent 2,827,726 to George F. Stradar, there is described and claimed an image-engraving plate suitable for engraving in the machine described in aforesaid Patent Re 23,914 and having one surface treated with a dye mixture of a pronounced color which, upon engraving, provides a marked contrast between the engraved surface and the body of the plate, thus giving a clear indication of the quality and the nature of the image engraved upon the plate.

The present invention constitutes an improvement on that described and claimed in aforesaid Patent 2,827,726 and provides an image plate which, when engraved, can be used not only for printing processes, by which a nearly unlimited number of copies may be reproduced, but also in photo'actinic processes where a lesser number of copies is required. The term photo-actinic processes is used herein and in the appended claims to refer to processes utilizing electromagnetic radiation of wave lengths shorter than visible light, for example ultra-violet light, and to distinguish from ordinary photographic reproducing processes involving the use of a negative with an emulsion coating sensitive to visible light.

In the case where only a small number of reproduced copies is desired, the image plate of the invention, after engraving, may be used in machines for making copies on photo-actinic paper and commercially available under the trademarks Ozalid and Breuning; in cases where a larger number of reproductions is desired, for example not exceeding a few hundred, such a plate may be used in machines for making copies on photo-ac-t-inic offset plates; in the event a very large number of reproduced copies is desired, the image plate, after engraving, may be used directly, or indirectly by means of stereo mats, in conventional letterpress printing. Thus, a single plate engraved in a single type of engraving machine can be used for three different types of image reproduction.

It is an object of the invention, therefore, to provide a new and improved image-engraving plate which may be used for image reproduction by photo-actinic processes.

It is another object of the invention to provide a new and improved image-engraving plate which may be used for image reproduction by photo-actinic processes or by letterpress printing.

In accordance with the invention, an engraving plate for reproducing images by either printing or photo-actinic ray-transmitting processes comprises an uniformly finished-surface sheet of deformable transparent plastic material, only one face thereof having a surface portion impregnated with a material having a low transmittance to ultra-violet light, the surface portion of the sheet material retaining substantially the original character of the finished surface. The term plastic, as used herein and in the appended claims, is intended to embrace all of the organic polymeric materials, particularly polymeric resins, capable of being placed in condition for molding or casting, whether those materials be of natural or synthetic origin. The term finished surface, as applied to a plastic sheet, is used herein and in the appended claims to refer to a commercially planar surface which may be, but is not necessarily, polished after molding or skiving.

Further in accordance with the invention, an engraving plate for reproducing images by either printing or photoactiuic ray-transmitting processes comprises an uniformly finished-surface sheet of deformable transparent plastic material. Only one face of the sheet has a surface portion impregnated with a material having a low transmittance, preferably substantially opaque, to ultra-violet light, particularly to wave lengths in the range of 360-400 m The latter material is advantageously a mixture of a dye and a mutual solvent for the dye and the plastic material of the sheet.

For a better understanding of the present invention,

together with other and further objects thereof, reference is had to the following description while its scope will be pointed out in the appended claims.

In impregnating the one surface of the image sheet with the dye mixture, the techniques described in aforesaid Patent 2,827,726, Stradar, may be followed for ensuring that the treated surface of the plate is not softened, chemically altered, or otherwise degraded but retains substantially its original physical and chemical character.

The image-engraving plate of the invention may be formed of any suitable material, for example, any of the thermo-plastic resins listed in the table below.

The dye to be included in the dye mixture is advantageous-ly one which is substantially opaque to ultra-violet light but also has a pronounced color which serves to show the natur of the finished engraving, as described in aforesaid Patent 2,827,726. Examples of dyes of special utility are those of the technical group called solvent dyes which have substantial opacity to ultraviolet light, particularly the azo and xanthene dyes. There Ethyl cellulose ether follows a listing of a number of these dyes suitable for use in treating the plastic plate of the invention.

Name: Color index Monoazo dyes- Oil Yellow 2681 11160 Yellow AB 11380 Orasol Yellow 30W 18820 Azosol fast Orange GA 18745A Lithofor Brown A 11285 Diazo dyes Oil Yellow GR 21230 Bismark Brown TSS Base 2l0l0B Xanthene dyes- Eosin Acid 3G 45395 D and C Orange No. 16 45371 Other dyes Auramine Base 4100B Waxoline Orange A 46 005B Fluorescent Purple 2G 36900 Calcofluor Yellow HEB (1) Fluorol OB (1) Fluorol 5GA 45550 Fluorol OBR (2) Uvitcx RS 49015 Blancophor R 40600 No Color Index number; commercially available from Calco Chemical Co. and American Cyanalmid Co.

No Color Index number; commercially available from General Dyestuif Co.

In general, the solvent is advantageously a normally liquid volatile organic solvent which dissolves and is substantially inert to both the dye and the plastic material of the plate.

The constituency of the solvent in any particular case will depend on the specific plastic and dye materials selected as well as upon the drying rate and temperature. Among the materials suitable for forming the imageengraving plate of the invention are the following, with a number of suitable solvents indicated for each plastic material:

Sheet Material Solvent Cellulose nitrate A lower aliphatic alcohol such as a methyl, ethyl, propyl, isopropyl, or butyl alcohol.

An ester of a lower aliphatic acid,

e.g., amyl, ethyl, or bntyl acetate and mixtures thereof; an aliphatic ketone, e.g., acetone, methyl ethyl ketone, diethyl ketone, and methyl isobutyl ketone.

A lower aliphatic alcohol such as a methyl, ethyl, propyl, isopropyl, or butyl alcohol; an ester of a lower aliphatic acid, e.g., amyl, ethyl, or butyl acetate and mixtures thereof; an aliphatic ketone, e.g., acetone, methyl ethyl ketone, diethyl ketone, and methyl isobutyl ketone.

A11 ester of a lower aliphatic acid, e.g., amyl, ethyl, or butyl acetate and mixtures thereof; an aliphat- 1c ketone, e.g., acetone, methyl ethyl ketone, diethyl ketone, and methyl isobutyl ketone; an alkylene halide, e.g., ethylene dichloride; an aromatic hydrocarbon, e.g., toluene.

Acetone, benzene, toluene, xylene,

ethyl acetate.

Polystyrne or Methyl methacrylate polymers.

Cellulose acetate, Cellulose acetate butyrate.

Vinyl chloride acetate polymers The solvents are listed in the preceding table in the order of decreasing dissolving action which will affect the rate at which the sheet is passing through the coating apparatus. The solvent can be a compatible mixture of various of the solvents listed, rather than a single one. For best results, the solvent is substantially completely vaporized in the drying of the treated plastic sheet; hence its chemical composition is not critical. Further, the precise concentration of the dye is not critical but it is advantageously close .to saturation to provide a high dye density although somewhat below saturation to avoid any possible precipitation on the surface of the treated sheet in the event of some evaporation of the solvent in handling, storing, and coating the sheet. The amount of thedye mixture used may be varied in accordance with the desired dye density in the treated sheet which, in turn, will depend upon the sensitivity of the reproducing medium to be exposed through the sheet, but generally one quart of the dye mixture will satisfactorily treat from 20,000 to 200,000 square inches of sheet material. The amount of the dye mixture actually applied depends, of course, on the rate at which the sheet is passed through the coating apparatus and this will, in turn, determine the depth of impregnation of the dye. As set forth in aforesaid Patent 2,827,726, this penetration is advantageously of the order of 0.0001 inch to be certain that it is less than the usual maximum deformation of the plate during the engraving process. If a higher density is desired in the treated sheet, it may be passed through the coating and drying apparatus a second time.

There follows, as one specific example, a satisfactory method of coating an image-engraving plate in accordance with the invention. A clear skived sheet of cellulose nitrate, having one surface finished by polishing under heat and pressure, was passed through a commercial Pott Devin gluing machine at the rate of approximately 20 feet a minute at room temperature of 70-80 F. In this machine, a film of dye mixture was applied to the sheet comprising a 2.3% solution of Oil Yellow 2681 in methyl alcohol. After coating, the sheet was passed through a drying chamber beneath a bank of infra-red heaters, the passage requiring approximately 3 minutes, while a counterfiow of air at room temperature limited the surface temperature of the sheet to approximately F.

In another embodiment of the invention, the nonactinic dye may be colorless, in which case it is advantageously mixed with an actinic dye of pronounced color to provide the desired contrast in the finished engraved plate. Such colorless nonactinic dyes are usually found in two general classes, certain fluorescent dyes and the ultra-violet absorbers commercially used for stabilizing plastics, such as salicyclic esters, hydroxybenzophenones, and hemetriazoles. Examples of such colorless nonactinic dyes follow. In each case, such dye may be mixed with any of the color dyes mentioned in aforesaid Patent 2,827,726 soluble in the particular solvent used for the colorless nonactinic dye:

Fluorols (General Class) 1 Lumogen (General Class) 1 Calcofluor White B 2 Potamine White CL 3 Phenyl salicylate 2-hydroxy-4-methoxybenzophenone Substituted benzotriazole 2,2-dihydroxy-4-methoxybenzophenone 1 No Color Index number; commercially available from LG. Farbenindustrie.

No Color Index number; commercially available from Calco Chemical Division of American Cyanamid Co.

3 No Color Index number; commercially available from E. I. du Pont de Nernours and Co.

A plastic lmage-engraving plate, treated on only the engraving surface with any of the dye and solvent mixtures as described above, is substantially opaque to ultraviolet light and particularly that Within the range of 360- 400 m and is thus suitable for use in photo-actinic processes either directly on photo-actinic paper or by photooffset plates and also may be used directly, or indirectly by means of stereo mats, for letterpress printing.

While there have been described what are at present considered to be the preferred embodiments of the invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention, and it is, therefore, aimed in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the invention.

What is claimed is:

1. An engraving plate for reproducing images by either printing or photo-actinic ray-transmitting processes comprising: an uniformly finished-surface sheet of deformable transparent plastic material, only one face thereof having a surface portion impregnated with a material having a low transmittance to ultra-violet light, said surface material retaining substantially the original character of the finished surface.

2. An engraving plate for reproducing images by either printing or photo-actinic ray-transmitting processes comprising: an uniformly finished-surface sheet of deformable transparent plastic material, only one face thereof having a surface portion impregnated with a material having a W transmittance to light of wave lengths in the range of 360-400 me, said surface material retaining substantially the original character of the finished surface.

3. An engraving plate for reproducing images by either printing or photo-actinic ray-transmitting processes comprising: an uniformly finished-surface sheet of deformable transparent plastic material, only one face thereof having a surface portion impregnated with a material substantially opaque to ultra-violet light, said surface material retaining substantially the original character of the finished surface.

4. An engraving plate for reproducing images by either printing or photo-actinic ray-transmitting processes comprising: an uniformly finished-surface sheet of deformable transparent plastic material, only one face thereof having a surface portion impregnated with a mixture of a dye having a low transmittance to ultra-violet light and a mutual solvent for said dye and said plastic material, said surface material retaining substantially the original character of the finished surface.

5. An engraving plate for reproducing images by either printing or photo-actinic ray-transmitting processes comprising: an uniformly finished-surface sheet of deformable transparent plastic material, only one face thereof having a surface portion impregnated with a mixture of an oil yellow 2681 (CI. 11160) dye and methyl alcohol, said surface material retaining substantially the original character of the finished surface.

6. An engraving plate for reproducing images by either printing or photo-actinic ray-transmitting processes comprising: an uniformly finished-surface sheet of deformable transparent plastic material, only one face thereof having a surface portion impregnated with a substantially 2.3% solution of an oil yellow 2681 (CI. 11160) in methyl alcohol, said surface material retaining substantially the original character of the finished surface.

. 7. An CngTaVlIlg plate for reproducing images by either printing or photo-actinic ray-transmitting processes comprising: an uniformly finished-surface sheet of deformable transparent plastic material, only one face thereof having a surface portion impregnated with a mixture of a. Xanthene dye and a mutual solvent for said dye and said plastic material, said surface material retaining substantially the original character of the finished surface.

8. An engraving plate for reproducing images by either printing or photo-actinic ray-transmitting processes comprising: an uniformly finished-surface sheet of deformable transparent plastic material, only one face thereof having a surface portion impregnated with a mixture of eosin acid 3G (CI. 45395) and methyl alcohol, said surface material retaining substantially the original character of the finished surface.

9. An engraving plate for reproducing images by either printing or photo-actinic ray-transmitting processes comprising: an uniformly finished-surface sheet of deformable transparent plastic material, only one face thereof having a surface portion impregnated with a mixture of a colorless nonactinic dye, a color actinic dye, and a mutual solvent for said dyes and said plastic material, said surface material retaining substantially the original character of the finished surface.

References Cited in the file of this patent UNITED STATES PATENTS 2,095,839 Sheppard et al Oct. 12, 1937 2,347,285 Russell Apr. 25, 1944 2,754,606 Williams July 17, 1956 2,827,726 Stradar Mar. 25, 1958 

1. AN ENGRAVING PLATE FOR REPRODUCING IMAGES BY EITHER PRINTING OR PHOTO-ACTINIC RAY-TRANSMITTING PROCESSES COMPRISING: AN UNIFORMLY FINISHED-SURFACE SHEET OF DEFORMABLE TRANSPARENT PLASTIC MATERIAL, ONLY ONE FACE THEREOF HAVING A SURFACE PORTION IMPREGNATED WITH A MATERIAL HAVING A LOW TRANSMITTANCE TO ULTRA-VIOLET LIGHT, SAID SURFACE MATERIAL RETAINING SUBSTANTIALLY THE ORIGINAL CHARACTER OF THE FINISHED SURFACE. 